6.4 Complex Methodology for Reverse Engineering …
547
6.4 Complex Methodology for Reverse Engineering
of Microcircuit Chip Topology
6.4.1 Comparative Analysis of Microscopic Methods of IC
Topologies
The element and component base of modern electronic systems include both complex
functional microcircuits with high integration levels (processors, memory circuits,
interface circuits) and microcircuits with relatively low integration levels (logical
microcircuit series, AD/DC-, AC/DC transducers, power control circuits, power
semiconductor devices).
As demonstrated above, operations of introducing hardware Trojans are the
simplest in the first group of microcircuits; at the same time, it is most difficult
to identify and neutralize them in this group.
However, the tasks of restoring topology and electrical circuits in order to identify
hardware Trojans must be solved for this entire group of microcircuits.
Of course, it is necessary to use different methods depending on the complexity of
the microcircuit. While analysis of microcircuits of the second group can usually be
performed using optical microscopy possibilities, complex submicron microcircuits
require the methods of electronic microscopy based on the principle of scanning the
chip surface with an electronic beam.
The transition to submicron and then to nanoscale topological standards severely
limited the possibilities of optical microscopy in analyzing the topologies of such integrated circuits and stimulated the development of the so-called fragmentary construction of the final holistic image. One of the features of transition to submicron element
base is design and process complication of the topology restoration process, which
is manifested in the increase in the number of switching layers. As a result, the
processes of alignment of image fragments and image layering have become the
critical stages of topology analysis during reverse engineering of IC chips.
Table 6.1 contains the results of the comparative analysis of various microscopy
methods used for microcircuit topology analysis. Each of them has both advantages
and disadvantages. For example, one of the advantages of optical microscopy is the
presence of color contrast and the possibility to obtain a high-quality panoramic
image; however, the limit resolution of this method amounts to not less than 350
nm. Scanning electronic microscopy, although providing a resolution that is better
by two orders of magnitude, has such significant downsides as the distortion of the
image frames, the complexity of alignment of the frames of neighboring frames, and
the non-linear dependence of the resolution quality on the energy of the electronic
beam.
Scanning electronic microscopy also creates certain difficulties during operation
with dielectrics of analyzed microcircuits.
547
6.4 Complex Methodology for Reverse Engineering
of Microcircuit Chip Topology
6.4.1 Comparative Analysis of Microscopic Methods of IC
Topologies
The element and component base of modern electronic systems include both complex
functional microcircuits with high integration levels (processors, memory circuits,
interface circuits) and microcircuits with relatively low integration levels (logical
microcircuit series, AD/DC-, AC/DC transducers, power control circuits, power
semiconductor devices).
As demonstrated above, operations of introducing hardware Trojans are the
simplest in the first group of microcircuits; at the same time, it is most difficult
to identify and neutralize them in this group.
However, the tasks of restoring topology and electrical circuits in order to identify
hardware Trojans must be solved for this entire group of microcircuits.
Of course, it is necessary to use different methods depending on the complexity of
the microcircuit. While analysis of microcircuits of the second group can usually be
performed using optical microscopy possibilities, complex submicron microcircuits
require the methods of electronic microscopy based on the principle of scanning the
chip surface with an electronic beam.
The transition to submicron and then to nanoscale topological standards severely
limited the possibilities of optical microscopy in analyzing the topologies of such integrated circuits and stimulated the development of the so-called fragmentary construction of the final holistic image. One of the features of transition to submicron element
base is design and process complication of the topology restoration process, which
is manifested in the increase in the number of switching layers. As a result, the
processes of alignment of image fragments and image layering have become the
critical stages of topology analysis during reverse engineering of IC chips.
Table 6.1 contains the results of the comparative analysis of various microscopy
methods used for microcircuit topology analysis. Each of them has both advantages
and disadvantages. For example, one of the advantages of optical microscopy is the
presence of color contrast and the possibility to obtain a high-quality panoramic
image; however, the limit resolution of this method amounts to not less than 350
nm. Scanning electronic microscopy, although providing a resolution that is better
by two orders of magnitude, has such significant downsides as the distortion of the
image frames, the complexity of alignment of the frames of neighboring frames, and
the non-linear dependence of the resolution quality on the energy of the electronic
beam.
Scanning electronic microscopy also creates certain difficulties during operation
with dielectrics of analyzed microcircuits.